According to their research people who were more fluent in "taboo words" were more likely to be fluent in mundane, neutral words, meaning that they actually had a wider vocabulary than other people.

"A voluminous taboo lexicon may better be considered an indicator of healthy verbal abilities rather than a cover for their deficiencies," the researchers wrote.

"People who use taboo words understand their general expressive content as well as nuanced distinctions that must be drawn out to use slurs appropriately. The ability to make nuanced distinctions indicates the presence of more rather than less linguistic knowledge, as implied by the POV [Poverty of Vocabulary] view."

In another study, researchers discovered that later the time you go to bed was also correlated with being intelligent.

During the study, the team found that many people who had a childhood IQ of less than 75 would go to be around midnight on the weeknights in early adulthood. The kids with the higher IQ, over 125 would end up going to bed later at around 1AM.